Generally in neurobiology fields, a microfluidic platform is used to observe and experiment growth of neurons and interactions between cells.
FIG. 1 is a diagram of a general structure of a neuron. Referring to FIG. 1, the neuron includes a cell body 1 including a nucleus 1a, a plurality of dendrites 2 growing from the cell body 1 and receiving a signal from an adjacent neuron, and an axon 3 growing from the cell body 1 and transmitting a signal to an adjacent neuron.
FIGS. 2 and 3 illustrate an example of a general microfluidic platform 10 applied to experiment the neuron of FIG. 1 (disclosed in Park J, Koito H, Li J, Han Microfluidic compartmentalized co-culture platform for CNS axon myelination research, Biomed Microdevices. 2009 Dec.; 11(6):1145-53).
As shown in FIGS. 2 and 3, the general microfluidic platform 10 includes, at one side, a pair of first reservoirs 11 spaced apart from each other and a soma compartment 12 communicating between the pair of first reservoirs 11. The general microfluidic platform 10 further includes, at the other side, a pair of second reservoirs 21 facing the pair of first reservoirs 11, and an axon compartment 22 communicating between the pair of second reservoirs 21. Also, the soma compartment 12 and the axon compartment 22 communicate with each other through a plurality of microchannels 30.
The general microfluidic platform 10 described above may be manufactured by completing a mater mold (not shown) having male shapes respectively corresponding to the first and second reservoirs 11 and 21, the soma and axon compartments 12 and 22, and the microchannels 30, pouring polydimethylsiloxane (PDMS) satisfactorily mixed with a catalyst into the master mold, and hardening the PDMS at about 75° C. Here, the pair of first reservoirs 11 and the pair of second reservoirs 21 are punched, and a cover glass is attached to the first and second reservoirs 11 and 21 and then coated so as to set conditions for culturing neurons. While culturing the neurons, the general microfluidic platform 10 is maintained to be wet therein.
The first and second reservoirs 11 and 21 contain neurons to be cultured, and are substantially used to supply and replace a culture medium. The soma and axon compartments 12 and 22 have a height of about 100 μm, and are spaced in which the neurons are stably cultured. The axon 3 of FIG. 1 grown by culturing the neuron passes through the microchannel 30. Here, the neuron at initial culturing has a round millet shape, and if a width and height of the microchannel 30 are high, the neuron may move to the axon compartment 22 on the opposite side. Thus, the microchannel 30 may have a height from about 2.5 to about 3 μm and a width per channel of about 10 μm so as to prevent the neuron from moving to an opposite compartment. In other words, in the soma compartment 12, the neuron is initially cultured and the cell body 1 including the nucleus 1a is located. Also, in the axon compartment 22, the axon 3 that passed through the microchannel 30 is located.
However, in the general microfluidic platform 10, initial neurons put into the first reservoir 11 move to and are randomly distributed in the soma compartment 12 with the culture medium. Here, the axon 3 of the initial neuron adjacent to the microchannel 30 may pass through the microchannel 30 and grown towards the axon compartment 22 located at the other side, but the axon 3 of the initial neuron that is not adjacent to the microchannel 30 may not pass through the microchannel 30 and may grow only inside the soma compartment 12. In other words, since the initial neurons are randomly distributed in the soma compartment 12, the number of axons passing through the microchannels 30 from among the initial neurons put into the first reservoir 11 may be low, and thus a probability of observing the axons 3 for an experiment may also be low.
Meanwhile, in order to perform an experiment corresponding to a signal transfer direction of the neuron, the axon 3 that passed through the microchannel 30 from the soma compartment 12 may form a synapse with the dendrite 2 of the neuron cultured in the axon compartment 22.
However, in the general microfluidic platform 10, the axon 3 of the neuron adjacent to the microchannel 30 from among the neurons supplied from the second reservoir 21 and cultured in the axon compartment 22 frequently passes through the microchannel 30 and forms a synapse with the dendrite 2 of the neuron cultured in the soma compartment 12. Accordingly, a probability of growing cells to correspond to a signal transfer direction is low, and it is difficult to secure a required experiment target.